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Odometer stopper or mileage blockers are devices used to prevent the odometer from counting the miles traveled. The device is installed in the vehicle's dashboard and operates by blocking the signal from the speedometer or odometer sensor. This stops the odometer from registering the miles driven and prevents any changes to the readings. The device is ideal for preventing changes to the odometer in stolen vehicles, preventing mileage fraud and preventing excessive wear and tear on vehicles by keeping the odometer readings low.

Although it may be illegal in some countries to tamper with the odometer readings on a vehicle, in some cases the use of the odometer stopper may be allowed. For example, in some states in the USA, odometer stoppers may be used on leased cars to prevent the lessee from exceeding the maximum mileage limit. In such cases, the device can be used to protect the lessee from incurring additional costs for exceeding the mileage limit.